The present disclosure relates generally to information handling systems, and more particularly to an information handling system featuring a BJT-based bi-directional level translator.
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
In conjunction with information handling systems, there are multiple chipsets and subsystems powered off multiple power rails with different voltage levels. Often a design engineer is faced with a task of interfacing subsystems signaling at different voltage levels (such as System Messaging Bus (SMB) level conversion). Typically to accomplish this task, voltage translator circuits based on Metal Oxide Field Effect Transistors (MOSFETs) are used. However, at lower signaling voltages, the problem becomes more difficult to resolve due to the lack of inexpensive MOSFETs with low gate threshold voltages (Vgs).
MOSFETs have traditionally been used to translate voltages from 2.5 V to 5 V. They easily lend themselves to these applications due to the indifference of MOSFETs to the direction of current in its conducting channel. In other words, a signal can propagate in either direction, forward or reverse. FIG. 1 illustrates a schematic diagram view for a typical MOSFET-based voltage translator 10. However, as signaling voltages drop lower than 2.0 V, the typical MOSFET-based voltage translator circuit can no longer work reliably due to a minimum Vgs voltage required to maintain the conducting channel in the MOSFET. Unfortunately, due to the manufacturing process limitations, discrete MOSFETs with lower than 1.5 V Vgs are difficult to produce at reasonable costs.
Accordingly, it would be desirable to provide method and apparatus providing level translation in an information handling system absent the disadvantages found in the prior methods discussed above.